Effects of various protein- and polysaccharide-based clarification agents on antioxidative compounds and colour of pomegranate juice

Abstract

The effects of natural sedimentation and clarification agents [protein-based (albumin, casein and gelatin) and polysaccharide-based (chitosan and xanthan gum)] on total phenolics, hydrolysable tannins, anthocyanins and antioxidant activity of pomegranate juice were investigated. While protein-based agents led to higher reductions in the contents of total phenolics (7.2–17.2%), hydrolysable tannins (16.7–59.5%) and anthocyanins (11.7–23.7%) (p<0.05) than natural sedimentation, polysaccharide-based agents had similar effects on these compounds, like natural sedimentation (p>0.05). The stabilities of β-punicalagin and α-punicalagin (the major hydrolysable tannins) against clarification were similar. Moreover, antioxidant activities of the samples clarified with polysaccharide-based agents were higher (2.4–26.6%) than those of the protein-based agents. For both high total phenolic, hydrolysable tannin and anthocyanins contents, as well as high antioxidant activity, we suggest that polysaccharide-based agents be used for the clarification of pomegranate juice. In fact, chitosan is especially recommended for this purpose since chitosan (10.3NTU) led to lower turbidity as compared to xanthan gum (20.0NTU).